I agree I would not suggest doing anything non-standard with it. And yes, it looks dated and ugly. But in some places visual appearance of widgets is not that important.
Often, boring UI:s are good. The tool should fade into the background and let the user focus on getting her work done.
While I love shiny things the real world accepts good enough solutions that are economic to develop.
Theoretically I just adore WPF:s scenegraph oriented paradigm since it feels the right way but... I've observed that for a large projects practically it needs a lot of work to get anything usefull done compared to forms. Perhaps the overall architecture is a bit big-org oriented where every tiny widget will have its own development team. Which is understandable but means for simple UI:s WPF might be a lot more expensive.
I haven't done anything massive with it myself but have just observed a few projects from my work. I hope there are counterexamples.